Modifications of Zein Biopolymer for Material Applications: Biopolymer Blends, Films, Bioactive Delivery Nanoparticles, and Nanofibers

Abstract

The need for sustainable and high-performance materials is becoming increasingly urgent as society confronts escalating environmental challenges and pressing healthcare demands. Zein, a protein derived from corn, offers promising potential as a renewable, biodegradable, and biocompatible material for various applications. However, its utility is hindered by intrinsic limitations, such as poor processability, inadequate mechanical properties, and limited thermal stability. This research aims to address these challenges through chemical modifications of zein, blending with complementary polymers, and employing advanced fabrication techniques to develop nanoparticles and nanofibers for targeted applications. The first part of this study focused on chemically modifying zein via esterification using fatty acid chlorides of varying chain lengths (C6, C10, and C16). The findings revealed that fatty acid-modified zein exhibited significantly enhanced hydrophobicity, improved melt processability, and superior tensile properties compared to unmodified zein. The introduction of fatty acid chains also acted as internal plasticizers, facilitating the creation of a melt-processable biopolymer suitable for scalable production. In the second phase, the modified zein (mZein) was blended with poly(butylene adipate-co-terephthalate) (PBAT) via melt extrusion to fabricate biodegradable films. The study explored the effects of varying blending ratios on the compatibility, morphology, and physicomechanical properties of the films. It was observed that the esterification with decanoic acid (C10) significantly enhanced mZein's compatibility with PBAT, enabling the formation of films with balanced mechanical and barrier properties. A composition of mZein/PBAT at 30/70 wt% exhibited optimal performance, achieving a tensile strength of 10.88 MPa, elongation at break of 561.41%, and a modulus of 105.63 MPa. Furthermore, the blend demonstrated superior oxygen barrier properties, reduced water vapor permeability, and improved disintegration rates, making it suitable for food packaging and agricultural applications. The third component of this research examined zein as a biopolymer matrix for nanoencapsulation of bioactive compounds, specifically quercetin and α-tocopherol. Zein nanoparticles (ZNPs) were fabricated using a green antisolvent co-precipitation method, achieving encapsulation efficiency of 96% with particle sizes ranging from 50 to 320 nm. Co-encapsulation of quercetin and α-tocopherol in various formulations revealed distinct release dynamics, with the Zein/Que/Toc (20:1:1) formulation demonstrating controlled release rates over 8 hours. ATR-FTIR and fluorescence spectroscopy highlighted the hydrogen bonding and hydrophobic interactions critical to the encapsulation mechanism. In the final phase, α-tocopherol-encapsulated zein was integrated with polyvinyl alcohol (PVA) to produce nonwoven fiber mats via solution blow spinning. These mats exhibited uniform fiber morphology (diameter: 350–796 nm), excellent mechanical properties, and sustained release of α-tocopherol over 24 hours. Cytotoxicity assessments confirmed high cell viability (>90%) and enhanced cell spreading, suggesting the potential for biomedical applications such as wound dressings. Overall, this research contributes significantly to the fields of biodegradable polymers and bioactive delivery systems. By overcoming the intrinsic limitations of zein through chemical modification and advanced processing techniques, this work offers a scalable framework for the development of high-performance sustainable materials. These findings have broad implications for applications in food packaging, agriculture, pharmaceuticals, nutraceuticals, and biomedical sciences, paving the way for more environmentally friendly and functional material solutions.